HaroldRowsdower said: but who's the octopus, clams, and shark?
Octopus is definitely ZEXAL's Ryouga from his hair style and color, I would say the shark is also Ryouga, given that he is called by his nickname 'Shark' by a good chunk of the ZEXAL cast but since it's blue and is chasing Yugi so maybe it's Kaiba? Not enough defining features to say for sure though, same with the clams.
